Constrained Control of Nonlinear DC Microgrids with Time-Varying Constant Power Loads

This study proposes a unified decentralised control scheme for dc microgrids comprised of boost converters and constant power loads. A control theoretic approach is presented, where analytic tools are used to derive the system model and prove the existence of a positive invariant set under the system dynamics. This property guarantees that the effect of constant power load demand fluctuations does not destabilize the system and limits high transients that can otherwise damage the electronic components. A careful design of the controller structure leads to rigorously proving closed-loop system stability, as well as allows the derivation of necessary conditions on the controller parameters that guarantee the desired behaviour. Hence, the results are not affected by the network topology nor require knowledge of the network parameters, enhancing the overall implementability of the proposed design. The proposed control scheme is tested in a simulated scenario, verifying the theoretic results and demonstrating network resilience to sudden load perturbations.